
But it's important to note that this theory, that we have before us a combination of two poems, is not universally accepted; one reason being that there are too many clean continuities from the beginning all the way to the end.
So with that, let's jump all the way to the end to see how this finishes nicely in a way that hearkens all the way back to how the whole psalm began:

יב) אַֽל־תִּ֭תְּנֵנִי בְּנֶ֣פֶשׁ צָרָ֑י כִּ֥י קָֽמוּ־בִ֥י עֵֽדֵי־שֶׁ֝֗קֶר וִיפֵ֥חַ חָמָֽס׃
(12) Do not turn me over to the maw of my foes; For false witnesses have risen against me, breathing threats of violence.
Here, nefesh, "life-breath," shows a secondary meaning, through metonymy - the throat or guilt, through which breath passes.
He is really onto something here, something which every other translation has completely missed out on. You can check out BibleHub or e-sword for some comparisons. . Most of the others render this as "will" or "desire." But Alter is right, of course, when says that on a literal level, "nefesh" refers to the "life-breath."
For a point of reference, here is a passage from Exodus that many of us recite on the Sabbath-morning:
(טז) וְשָׁמְר֥וּ בְנֵֽי־יִשְׂרָאֵ֖ל אֶת־הַשַּׁבָּ֑ת לַעֲשׂ֧וֹת אֶת־הַשַּׁבָּ֛ת לְדֹרֹתָ֖ם בְּרִ֥ית עוֹלָֽם׃ (יז) בֵּינִ֗י וּבֵין֙ בְּנֵ֣י יִשְׂרָאֵ֔ל א֥וֹת הִ֖וא לְעֹלָ֑ם כִּי־שֵׁ֣שֶׁת יָמִ֗ים עָשָׂ֤ה יְהוָה֙ אֶת־הַשָּׁמַ֣יִם וְאֶת־הָאָ֔רֶץ וּבַיּוֹם֙ הַשְּׁבִיעִ֔י שָׁבַ֖ת וַיִּנָּפַֽשׁ׃ (ס)
(16) The people of Israel shall observe the Sabbath; Doing the Sabbath throughout their generations; A covenant-eternal!
(17) Between me, and between the people of Israel; it is a sign for eternity; For in six days YHWH made the heavens and the earth, while on the seventh day, he rested... and was refreshed!

(יב) אַֽל־תִּ֭תְּנֵנִי בְּנֶ֣פֶשׁ צָרָ֑י כִּ֥י קָֽמוּ־בִ֥י עֵֽדֵי־שֶׁ֝֗קֶר וִיפֵ֥חַ חָמָֽס׃
(12) Do not turn me over to the maw of my foes; For false witnesses have risen against me, breathing threats of violence.
Don't give me over to
- The life-breath of my enemies;
- For false witnesses have risen against me;
- Breathing threats of violence!
Let's look back at an image from the beginning:
(ב) בִּקְרֹ֤ב עָלַ֨י ׀ מְרֵעִים֮ לֶאֱכֹ֪ל אֶת־בְּשָׂ֫רִ֥י צָרַ֣י וְאֹיְבַ֣י לִ֑י הֵ֖מָּה כָשְׁל֣וּ וְנָפָֽלוּ׃
(2) When evil-doers assail me to devour my flesh— my foes and my enemies - it is they who stumble and fall.
Here it is with the JPS translation:

Some people are approaching (ק-ר-ב) in order to "slander," though the Aramaic uses א-כ-ל, (which in Hebrew we recognize as "to eat") the Judeans. Then, if you open up a Strong's Concordance for the word קרציהון, you will see that it means "to eat the morsels of," or "to chew," and figuratively, "to slander." To eat the flesh of someone seems to have been an idiom for slander.
So after all the fun we had last session in concretizing the prayer-poem's earlier image of the poet being surrounded by enemies with cannibalistic intentions, we now see the poet doing double-duty, in referring metaphorically to enemies who are speaking against him falsely, an image that now becomes explicit in this chiasm at the poem's tail end!

Oftentimes, it brackets in a significant, self-contained literary of unit - such as a poem, in our case - and invites us to reflect upon where we started, and how far we might have come.
So let's reflect for a moment before pressing on to the coda. Here is one possible summary in bullet form of what we've seen so far (remember, still two verses left):
- 1-3 Declaration of confidence in YHWH - my light and my salvation;
- 4-6 The poet only seeks out one thing; living in tranquility with YHWH in the intimacy of YHWH's own home; and the poet has no doubt that he will merit this;
- 7-12 The poet seems, quite suddenly, insecure, begging YHWH never to leave him alone.
(יג) לׅׄוּלֵׅׄ֗אׅׄ הֶ֭אֱמַנְתִּי לִרְא֥וֹת בְּֽטוּב־יְהוָ֗ה בְּאֶ֣רֶץ חַיִּֽים׃
(13) Had I not trusted in seeing the YHWH-goodness in the land of the living...
Any thoughts?
To me, the affect of the unfinished sentence of verse 13 demonstrates that the prospect of not having conviction in ultimately seeing YHWH-goodness is so terrible such that the psalmist does not even want to utter the consequences!
This is quite common in the TaNaKh, and it even has a name: aposiopesis.

Check out e-sword or BibleHub to see the various decisions translators have made over the years. Notice anything particularly striking?

He shrinks from stating the consequences, He would have fainted, or despaired, or lost all faith in religion... By an effort of faith, the psalmist saved himself from the despair which threatened to seize upon him, and assured himself that he would yet experience "the goodness of the Lord" in some merciful interposition and deliverance, while he still remained on earth, before he "went whence he should not return—to the land of darkness and the shadow of death, a land of darkness as darkness itself, and of the shadow of death, without any order, and where the light is as darkness".
Here is another comment, responding to the King James version (I had fainted, unless I had believed to see the goodness of YHWH in the land of the living.)
The words “I had fainted” are not in the original. The sentence is a broken one, such as one utters under strong emotion, suggesting possibilities, but leaving the hearer or reader to supply them for himself. “O had I not believed to see the goodness of Jehovah in the land of the living”—and then he breaks off, and we are left to imagine what dreadful thing would have happened.

And with that, here's one more comment to ponder, this one from the Cambridge Bible Commentary:
The word for "unless" is marked with dots in the Massoretic text as probably spurious. Omitting it, we may render;
I believe that I shall see &c.
Interesting! How does this one change the reading!
Here are a few questions worth thinking about in light of this:
- Does this one word make a difference of substance?
- Is there any affect on the broader arc of this poem by retaining the word versus leaving it out?
- What is at stake in meaning here?
- Which reading do you prefer?
(יד) קַוֵּ֗ה אֶל־יְה֫וָ֥ה חֲ֭זַק וְיַאֲמֵ֣ץ לִבֶּ֑ךָ וְ֝קַוֵּ֗ה אֶל־יְהוָֽה׃
(14) Hope to YHWH! Be strong and of good courage! O, hope to YHWH!
This refers to when the first word of a verse is echoed again towards the end of the verse, and usually has the effect of emphasizing whatever words it is encircling.
Here's another example:
יְהִֽי־שָׁל֥וֹם בְּחֵילֵ֑ךְ שַׁ֝לְוָ֗ה בְּאַרְמְנוֹתָֽיִךְ׃ (ח) לְ֭מַעַן אַחַ֣י וְרֵעָ֑י אֲדַבְּרָה־נָּ֖א שָׁל֣וֹם בָּֽךְ׃ (ט) לְ֭מַעַן בֵּית־יְהוָ֣ה אֱלֹהֵ֑ינוּ אֲבַקְשָׁ֖ה ט֣וֹב לָֽךְ׃
(7) May there be peace in your ramparts, tranquility in your palaces!
(8) For the sake of my brethren and friends, may I speak of your peace.
(9) For the sake of the House of YHWH our Elohim, may I seek out your good.

Look back to our bullet-point summary from a few minutes ago. How does the "arc" of the poem vary, depending on how we answer this question?
